This invention relates to bicycle frame construction, and in particular to bicycle frames having rear suspensions, yet having easy access and removal of the rear wheel.
Bicycles and motorcycles were originally built with rigid frames. As the horsepower, weight and speed of motorcycles increased, and they began to be used off road, both front and rear wheel suspensions were developed and have now reached a very high degree of sophistication. Many different arrangements have been used for springing and damping rear suspensions, including complex linkages. The majority of rear suspensions on two wheeled vehicles use a fork-type rear swingarm as the main rear suspension structural member, regardless of the type of springs, damping devices and linkages used. The fork-type swingarm has a member on each side of the rear wheel, these two members being fixed together at the front pivot area, and joined at the rear by a rear axle which clamps the wheel between the two members. Changing the wheel, tire, brake, rotor, or wheel bearings requires removal of the rear axle from the swingarm, with attendant problems relating to reinstallation and alignment.
Automobiles have for many years used cantilevered stub axles which allow wheels, brakes, and so on to be removed easily, without removing the axle from the swingarm. A few two-wheeled vehicles have used a single-sided swingarm, which is generally a large section tubular member down one side of the wheel, the tubular member being attached at its front to the frame with a bearing set mounted on a single axis. Because the side loads on the wheel are transferred through this tubular member in torsion only, the member is large and heavy, yet provides only mediocre lateral and torsional rigidity.
This invention relates to improvements to the apparatus set forth above and to solutions to some of the problems raised or not solved thereby.